One-handed cam action fish tape puller
FIELD OF THE INVENTION. 
     This invention relates to tools for manipulating thin, elongated steel strips or tapes. More particularly, the invention relates to tools which are useful for gripping and pulling steel leader tapes, referred to as fish tapes, which are temporarily attached to electrical wires and then used to pull the wires through passageways behind building walls. 
     DESCRIPTION OF BACKGROUND ART. 
     Fish tapes are flexible steel tapes available in various lengths and used to &#34;fish&#34; attached electrical wires through walls and floors of structures in which new electrical wiring is being installed. A typical fish tape has a hook at one end adapted to attachment to the end of an electrical wire. The hooked end of the tape is inserted into the opening of a conduit or other passageway through which is it desired to string an electrical cable. The tape is then fed into the conduit by pushing on the slack end, until the hook emerges from the conduit. The hook is then attached to the end of the electrical cable. After the hook has been attached to the end of the cable, a pulling force is applied to the opposite end of the tape, pulling the tape and attached cable through the conduit. 
     Typical fish tapes are 1/4&#34; to 5/16&#34; wide, about 1/16&#34; thick, and are supplied in reels containing 100 or 200 feet of tape. Frequently, substantial frictional resistance is encountered between the surfaces of the electrical wires and the walls of the conduits or passageways through which the wires are being pulled. Overcoming this frictional resistance makes it necessary to exert a large tensile force on the free end of the fish tape in pulling the wire all the way through the passageway. 
     Since it is difficult to exert a large pulling force on the free end of a fish tape with bare hands, pliers are sometimes used to grasp the free end of the fish tape to permit application of a larger pulling force. However, in practice, the jaws of the pliers frequently slip off of and damage the fish tape. Thus, the use of pliers provides a less than satisfactory solution to the problem of exerting a large pulling force on the fish tape. 
     In an effort to improve upon the pliers as a tool for pulling fish tapes, various tools have been devised. These include tools disclosed in the following U.S. patents: 
     Goodall, U.S. Pat. No. 1,880,431, Oct. 4, 1932, Tool For Forcing and Drawing an Element Through Conduits; Patterson, U.S. Pat. No. 1,939,187, Dec. 12, 1933, Fish Tape Puller; Hughes, U.S. Pat. No. 2,736,532, Feb. 28, 1956, Tool For Pushing or Pulling Fish Tape Through a Conduit; Ehrens, U.S. Pat. No. 3,763,722, Oct. 9, 1973, Gripping and Pulling Tool for Retracting Guide Tapes From Conduit While Pulling Electrical Wires Into the Conduit. 
     &#34;Lopes, U.S. Pat. No. 4,746,099, May 24, 1988, Cam Action Fish Tape Puller present inventor disclosed an improved fish tape puller using cam action jaws. The present invention was conceived of to provide an improved fish tape puller which can be operated with a single hand. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is to provide a fish tape pulling tool which can be manipulated using only one hand. 
     Another object of the present invention is to provide a tool capable of exerting a large pulling force on a fish tape without damaging it. 
     Another object of the invention is to provide a fish tape pulling tool which can produce a uniform pulling force on a fish tape, thereby minimizing the possibility of kinking the fish tape. 
     Another object of the invention is to provide a fish tape pulling tool having a minimum number of parts, thereby minimizing the cost of fabrication of the tool. 
     Another object of this invention is to provide a fish tape pulling tool having a pair of substantially identical parts, thereby minimizing the cost of manufacturing the tool. 
     Another object of the invention is to provide a fish tape pulling tool which is simply and easily operated. 
     Various other objects and advantages of the present invention, and its most novel features, will become apparent to those skilled in the art by perusing the accompanying specifications, drawings and claims. 
     It is to be understood that although the invention disclosed herein is fully capable of achieving the objects and providing the advantages described, the characteristics of the invention described herein are merely illustrative of the preferred embodiment. Accordingly, I do not intend that the scope of my exclusive rights and privileges in the invention be limited to details of the embodiments described. I do intend that equivalents, adaptations and modifications of the invention reasonably inferable from the description contained herein be included within the scope of the invention as defined by the appended claims. 
     SUMMARY OF THE INVENTION 
     Briefly stated, the present invention comprehends an improved tool for gripping and pulling a steel fish tape. The improved fish tape puller according to the present invention has two identical, generally flat members of uniform thickness. Each identical handle member has in plan view a generally flat upper wall surface, and curvilinear outer and lower wall surfaces, each having an indentation. The two handle members are pivotably joined to one another by means of a pivot pin disposed perpendicularly to the thickness dimension of the handle members. The pivot pin is located on the common longitudinal center line of the two handle members, a slight distance back from the inner wall surface of the handle member. 
     Each handle member has a convex inner wall surface near the pivot pin. One flat, rear planar surface of each handle member has a notch cut downward into the surface. The notch has a flat, vertical transverse surface forming a flat anvil plane disposed perpendicularly to the longitudinal axis of the handle member and displaced longitudinally outwards from the pivot pin. The notch is cut downwards approximately halfway through the thickness dimension of the handle member, and has a flat longitudinal wall surface parallel to the front and rear wall surfaces of the jaw member. 
     The two handle members are joined with their bottom flat notch-wall surfaces in sliding contact. Thus positioned, the convex front or inner surface of each handle member is eccentrically disposed with respect to the axis of the pin, thereby serving as a cam surface. Pivoting the handle members out of longitudinal alignment causes each convex front cam surface to move closer to an adjacent anvil plane sufficiently to grip a fish tape between the front cam surface and the anvil plane. The indentations in the outer and lower edge walls of the handle members are adapted to engagement by the fingers of a single handle. Also, the handle members are relatively short, permitting the tool to be held in a single hand with the handle members in a longitudinal alignment, while a fish tape is inserted between a cam surface and adjacent anvil plane on either side of the tool. Then, the handle members can be pivoted upwards to narrow the space between the cam surface and anvil plane, gripping the fish tape therebetween. Thus, by using the tool according to the present invention, a fish tape may be engaged, gripped and pulled, all while holding the tool in a single hand. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation view of the one-handed cam action fish tape puller according to the present invention, showing the tool in an open position with a fish tape inserted into the tool. 
     FIG. 2 is a lower plan view of the tool of FIG. 1. 
     FIG. 3 is a rear elevation view of the tool of FIG. 1. 
     FIG. 4 is a front elevation view of the tool of FIG. 1, showing a fish tape being gripped by the tool in a closed position. 
     FIG. 5 is a front elevation view of an alternate embodiment of the tool of FIG. 1, showing a fish tape being gripped by the tool in a closed position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS. 1 through 4, a one-handed cam action fish tape puller according to the present invention is shown. As shown in the Figures, the tool 10 includes left and right half handle members 11 which are identical. Each identical handle member 11 of tool 10 may be visualized as being formed from a block of uniform thickness material having flat and parallel front and rear wall surfaces 12 and 13, respectively. The cross-sectional shape of each handle member 11, as shown in the front elevation view of FIG. 1, is that of an irregular polygon having curved sides walls, the details of which side walls are described below. As a rough approximation, the cross-sectional shape of each handle member 11 may be described as a slightly horizontally elongated, quasi-rectangular shaped body having a generally flat upper edge wall surface 14, a convex inner edge wall surface 15, a concave, indented outer edge wall surface 16, and a concave, indented lower edge wall surface 17. 
     As shown in FIGS. 1 through 3, that portion of the rear wall surface 13 of each handle member 11 near convex inner edge wall 15 is cut away or relieved by a notch 18 which extends perpendicularly inwards from the rear wall surface to a parallel recessed longitudinal plane 19 located approximately half way through the thickness dimension of the handle member. Notch 18 extends from the inner edge wall 15 of handle member 11 longitudinally a distance of approximately one-third the length of the handle member, terminating in a vertically disposed transverse wall surface 20 which spans the width of the handle member and which extends perpendicularly forward from the recessed longitudinal plane 19. 
     As shown in FIGS. 1-3, two identical handle members 11 are pivotably joined together to comprise tool 10. For purposes of description, one of the two identical handle members 11, 11L, is referred to as a left-hand handle member, while the other handle member is referred to as a right-hand handle member 11R. Prior to assembly of handle members 11R and 11L into tool 10, one handle member, 11R, is rotated 180 degrees about its longitudinal axis relative to handle member 11L, placing the front wall surface 12 of left-hand handle member 11L in co-planar alignment with rear wall surface 13R of right-hand handle member 11R. Similarly, the relative positioning of the two handle members 11L and 11R places the rear wall surface 13L of left-hand handle member 11L in coplanar alignment with front wall surface 12R of right-hand handle member 11R. 
     With left and right handle members 11L and 11R positioned as described above, the recessed longitudinal wall 19L of notch 18L is in flush contact with recessed longitudinal plane wall 19R of right-hand handle member 10R. The inner portion of each handle member 11 is provided with a through-hole 21 extending through the thickness dimension of the handle member, extending through recessed longitudinal plane wall 19 and front wall surface 12. Hole 21 is positioned approximately on the longitudinal center line of handle member 11, slightly inwards from the apex 22 of convex inner edge wall 15. A double-headed pivot pin 23 extends through holes 21L and 21R of left and right handle members 11L and 11R. Thus joined, left and right handle members 11L and 11R may be pivoted in a plane parallel to the front and rear wall surfaces 12 and 13 of the handle members, the recessed planes 19L and 19R sliding against one another. 
     The convexly curved front wall surface 15 of each handle member 11 has an apex 22 which has a curvature which is greater than that of a circular surface. Preferably, the radius of curvature of apex 22 is also eccentrically located with respect to the pivot hole 21. Therefore, when the two handle members 11 are pivoted with respect to one another, apex 22 of each handle member approaches more closely to an adjacent transverse edge wall 20 of a notch 18. Thus, transverse edge wall 20 forms an anvil plane, allowing a fish tape A inserted between an apex 22 and anvil plane 20 to be tightly squeezed therebetween, when the two handle members are pivoted upwards out of longitudinal alignment, as shown in FIG. 4. 
     As shown in FIGS. 1-4, the lower edge wall 17 of handle member 11 preferably has a curvilinear concave indentation 24 adapted to provide a secure gripping surface for one or more fingers. Similarly, outer transverse edge wall 16 of each handle member 11 is preferably provided with a curvilinear indentation 25 adapted to provide a secure gripping surface for one or more fingers. 
     FIG. 5 illustrates a modified version 30 of the tool 10, in which each handle member 31 is provided with an aperture 44. Apertures 44 in handle members 31 reduce the weight of tool 30, without compromising its strength. Also, as shown in FIG. 5, apertures 44 may be used as finger holes for grasping the tool handle members 31. Thus, modified tool 30 may be grasped exteriorly, as shown in FIG. 4, or interiorly, as shown in FIG. 5.